1. Field of the Invention
The present invention relates to improved methods and systems for analyzing pyrolysis product gases, and more particularly, but not by way of limitation, to improved methods and systems for analyzing pyrolysis product gases during the production thereof.
2. Description of the Prior Art
The pyrolysis of a substance into one or more other substances is well known. Pyrolysis involves the application of heat to one or more compounds whereby the compounds decompose or higher molecular weight compounds are formed. Hydrocarbons are commonly subjected to pyrolysis to produce lower molecular weight compounds. For example, the pyrolysis of methane at about 1300.degree. C. brings about the formation of carbon black and hydrogen. The pyrolysis of gaseous alkanes at from about 500.degree. to about 600.degree. C., brings about the decomposition of the alkanes and is commonly referred to as thermal cracking.
In industry, and particularly in the petroleum and chemical industries, it is often desirable and/or necessary to subject compounds or substances to pyrolysis and to determine the particular products and amounts thereof produced thereby. For example, core samples from subterranean earth formations are subjected to pyrolysis and the products produced thereby analyzed to determine the hydrocarbon content of the samples and other information relative to the subterranean earth formation from which the samples were taken. Heretofore, pyrolysis testing has been carried out by placing a compound or substance to be pyrolyzed in a pyrolysis oven and heating the substance in the presence of an inert gas such as helium to a temperature level whereby pyrolysis occurs. The resulting pyrolysis product gases mixed with the inert gas utilized are analyzed using conventional analytical instruments such as a gas chromatograph.
In order to collect and analyze all of the pyrolysis product gases produced, a trap is utilized which retains the gases, such as by condensing and accumulating the condensed gases, after which the condensed gases are revaporized and analyzed. Where the pyrolysis of a substance is carried out under increasing temperature conditions and it is desirable to collect and analyze the product gases produced over different temperature ranges and/or where the pyrolysis is carried out at a constant temperature and it is desirable to collect and analyze portions of the gases produced separately according to time period, the heretofore used procedure requires that the pyrolysis reaction be carried out in two or more steps which is extremely difficult and time consuming.
By the present invention a method and system for collecting and analyzing pyrolysis product gases in two or more portions while carrying out the pyrolysis reaction in a single continuous step are provided. In addition, a portion of the pyrolysis product gases produced during the reaction is analyzed while an additional portion is being collected thereby reducing the overall time required for a full analysis of the gases to be carried out.